Babbage Flight

Babbage will be launched this Saturday morning between 10:30am and 11am, from Berkshire. Landing prediction is SW of Newbury.

The flight is a single balloon with 2 payloads, each one transmitting SSDV (images) and telemetry.

The main payload is called PIE. This has a cutdown mechanism that will release the second payload (TED) at 39km or when it senses a burst. Obviously 39km isn’t guaranteed even though the payloads are both relatively lightweight (less than 400g total) and the balloon is a 1600g Hwoyee filled with H2. 39km is 31 metres over Felix Baumgartner’s jump altitude, in case you wondered why it was chosen!

Both trackers are model A Pi boards each with UBlox GPS, NTX2 transmitter, Pi Camera module. TED’s camera is where his right eye used to be, and will look outwards for a normal view. PIE’s camera is directly above TED, looking down. So for most of the flight it will mostly see the top of TED’s head.

Flight Plan

Both payloads change what they do with their cameras depending on altitude. At low altitude (<2km) the transmitted images are small (320x240) and above that larger images (512x384). Also, both are programmed to take a short video of when Babbage is released. Depending on timing between the camera side and the transmission side, there may be a short period when no image is transmitted while the camera is recording video.
Additionally, full resolution 5MP images will be taken and stored when above 2km.
PIE is set to release TED as soon as it detects an altitude of 39000m or greater. This check is done on every new reading from the GPS and triggers a MOSFET-driven resistor cutdown, which should release TED after 2 seconds or so.
Tracking

To configure dl-fldigi just choose BABBAGE in the drop-down list, choose TED or PIE (makes no difference as they have the same settings) then hit autoconfigure. Or do it manually: Carrier shift 600Hz, 600 baud, 8 bits, 2 stop bits. Nominal frequencies are 434.200MHz (TED) and 434.250MHz (PIE).

To view the images as they come in, choose View ? SSDV in the menu. You don’t need to do anything else different to normal. You will see the binary image data coming in between telemetry strings, but of course it will just look like garbage. So long as you see the lime-green “Successfully decoded image packet” window then all is good. Telemetry is interlaced with the SSDV packets so you’ll see that coming in too.

Links

Live streams from launch site and chase car: http://www.batc.tv/streams/ukhas and http://www.batc.tv/streams/ukhas2

All SSDV images: http://ssdv.habhub.org (or you can select either payload with http://ssdv.habhub.org/TED or http://ssdv.habhub.org/PIE)